1. Field of the Invention
The present invention relates to an electronic endoscope system including a scope having a solid image sensor provided at a distal end thereof to generate image-pixel signals, an image-signal processing unit that produces a video signal on the basis of the image-pixel signals, and a TV monitor for reproducing and displaying an image in accordance with the video signal.
2. Description of the Related Art
In general, in such an electronic endoscope system, a component-type color video signal is produced on the basis of image-pixel signals obtained from a solid image sensor, such as a CCD (charge-coupled device) image sensor, to reproduce an image of high quality on a TV monitor. Usually, the component-type color video signal is composed of three-primary-color video signal components and a compound-synchronizing-signal component which includes various synchronizing signals, such as a horizontal synchronizing signal, a vertical synchronizing signal and so on.
As is well known, the compound-synchronizing-signal component is produced as a voltage signal, and the peak-to-peak level of the voltage signal is standardized to, for example, 4 volts. Thus, a medical TV monitor, used in the electronic endoscope system, is designed in accordance with the compound-synchronizing-signal component exhibiting the peak-to-peak level of 4 volts.
Since the medical TV monitor is expensive, a domestic TV monitor may be frequently substituted for the medical TV monitor. Nevertheless, domestic TV monitors are not designed so as to accept the compound-synchronizing-signal component exhibiting the peak-to-peak level of 4 volts. Thus, the domestic monitors cannot properly function and display an image even though being connected to the image-signal processing unit.
Especially, after an electronic endoscope system with a medical TV monitor is introduced into a medical facility, when the medical TV monitor is replaced by a domestic TV monitor, or when a domestic TV monitor is added to the introduced electronic endoscope system, a problem will occurs.
Therefore, an object of the present invention is to provide an electronic endoscope system comprising a scope having a solid image sensor provided at a distal end thereof to generate image-pixel signals, and an image-signal processing unit that produces a video signal on the basis of the image-pixel signals, wherein a peak-to-peak level of the synchronizing-signal component of the video signal can be manually and easily changed such that various types of TV monitors can accept the video signal.
In accordance with an aspect of the present invention, there is provided an electronic endoscope system including a scope having a solid image sensor provided at a distal end thereof to generate image-pixel signals, and an image-signal processing unit that produces a video signal based on the image-pixel signals. In the electronic endoscope system, an alteration alters a peak-to-peak level of a synchronizing-signal component of the video signal, and an manual setting system manually operates the alteration system to perform the alteration of the peak-to-peak level of the synchronizing-signal component.
Preferably, the manual setting system is constituted such that the alteration of the peak-to-peak level of the synchronizing-signal component is stepwise performed by the alteration system.
The alteration system may comprise a multiplier, and the manual setting system comprises a manual digital switch that produces code data, a multiplier-factor of the multiplier being altered in accordance with the code data produced by the manual digital switch.
Optionally, the alteration system comprises a voltage-controlled amplifier, an amplification factor of which is altered in accordance with a level of a voltage signal applied thereto. In this case, the manual setting system may comprise a manual digital switch that produces code data, and a voltage signal generator that generates the voltage signal such that the level of the voltage signal is altered in accordance with the code data produced by the manual digital switch.
In the alteration system comprising the voltage-controlled amplifier, the manual setting system may comprise a storage system that stores voltage data, a voltage signal generator that generates the voltage signal such that the level of the voltage signal is altered in accordance with the voltage data stored in the storage system. In this case, a manual-altering system that manually alters the voltage data stored in the storage system. Preferably, the storage system comprises a non-volatile memory, such as an electrically erasable programmable read-only memory.
In an electronic endoscope system according to another aspect of the present invention, a first alteration system alters a peak-to-peak level of a synchronizing-signal component of the first video signal, a first manual setting system manually operates the first alteration system to perform the alteration of the peak-to-peak level of the synchronizing-signal component of the first video signal, a second alteration system alters a peak-to-peak level of a synchronizing-signal component of the second video signal, and a second manual setting system manually operates the second alteration system to perform the alteration of the peak-to-peak level of the synchronizing-signal component of the second video signal.